Donna Edwards and Chris Van Hollen. (Mark Gail for The Washington Post)

Democratic Senate candidate Donna F. Edwards was endorsed Monday by two of the Prince George’s County Democrats hoping to succeed her in the House of Representatives, even as her rival, Rep. Chris Van Hollen (D-Md.), launched an ad calling her an ineffective lawmaker.

Van Hollen and Edwards are locked in an intense battle for the Democratic nomination for the Senate seat being vacated by retiring Sen. Barbara A. Mikulski (D-Md). A Washington Post-
University of Maryland poll
released last week gave Edwards a statistically insignificant four-point lead in the race, with just weeks to go before the April 26 primary.

Van Hollen’s ad relies on a ranking from the website InsideGov, which looked at how many bills sponsored by a lawmaker made it through committee in the last Congress.

“Edwards was ranked one of the least effective members of Congress . . . and the least willing to find common ground,” the narrator says. The ad then quotes a Washington Post editorial comparing Edwards to “tea party Republicans.”

The spot, Van Hollen’s first attack ad of the campaign, comes in response to one released by Edwards last week accusing the congressman of betraying progressive values.

That ad was the first paid for by Edwards herself. The congresswoman struggled to raise money last year but took in more than $1 million in the first three months of 2016. However, a super PAC run by the Democratic women’s group Emily’s List has been airing ads in support of Edwards for months.

In his ad, Van Hollen calls Edwards’s attacks false, as he has in debates and forums across the state.

Edwards, likewise, has pushed back on Van Hollen’s characterization of her as ineffective, saying she has worked across the aisle on the science and transportation committees.

In a statement Monday, Edwards spokesman Benjamin Gerdes said the congresswoman’s campaign was “disappointed” by Van Hollen’s “negative, personal attacks.”

Edwards, who would be the first African American senator from Maryland and has based her campaign on the need for more diversity in that chamber, was endorsed Monday by former lieutenant governor Anthony G. Brown and state Del. Joseline A. Peña-Melnyk, both of whom are vying for the Democratic nomination for Edwards’s congressional seat.

“From her fierce advocacy on domestic violence issues to defending women’s rights, Donna has been a champion for Maryland women and their families,” Brown said in a statement.

Peña-Melnyk, who was born in the Dominican Republic, said: “Perspective matters, and as a woman of color, it is important to me that our voices are represented in the US Senate.”

Edwards has a rocky relationship with other politicians in her home county of Prince George’s. County Executive Rushern L. Baker III (D) and state senators Joanne C. Benson, Ulysses Currie and Victor R. Ramirez, among others, have endorsed Van Hollen.

“It’s become apparent that the people who know her best are not supporting her,” Baker said on a conference call last week organized by the Van Hollen campaign to criticize Edwards.

But the The Post-University of Maryland survey found Edwards leading Van Hollen in Prince George’s 77 percent to 18 percent. Van Hollen, who lives in Kensington, was leading by a similar margin in Montgomery County.

Neither Edwards nor Van Hollen has endorsed candidates in the races to succeed them.